In recent years, enhancement of an NC-program creation support function of a program creation device has been promoted, such that an operator can easily create an NC machining program by setting a coordinate value of a workpiece in a program creation device, while looking at a production drawing. Further, a program creation device that directly reads CAD data modeled by a designer by using a CAD system into the program creation device to create an NC machining program has been proposed.
When CAD data including only product shapes is handled, machining instructions and dimension display data described in the production drawing may not be reflected in the CAD data, and thus the machining instructions and dimension display data described in the production drawing need to be reflected in the NC machining program so as not to cause a machining defect.
In Patent Literature 1, an extension line extending from both ends of a profile line is displayed on a display screen, in addition to the profile line connecting from a machining change point to a machining change point of a machining pattern of an object to be machined acquired by an input unit or from a memory. The extension line on a machining start side of the profile line to be selected is selected on the screen according to a machining procedure, and then the extension line on the machining start side of the profile line to be selected next is selected on the screen. This process is repeated to set the machining procedure of the object to be machined.